Double-acting hydraulic jack



May 16, 1950 K. J. MOGK DOUBLE ACTING HYDRAULIC JACK 4 Sheets-Sheiet 1 Filed Sept. 30, 1948 INVENTOR. mad/10,;

ATTORNEY May H5, 1950 K. J. MOGK DOUBLE ACTING HYDRAULIC JACK {1 Sheets-Sheet 3 Filed Sept. 30, 1948 By 151/ Way/2 ATTORNEY IN VEN TOR. W m/ J 1/0 4 [4% 7 Patented May 16, 1950 DOUBLE-ACTING HYDRAULIC JACK Karl J. Mogk, Peoria, 111., assignor to Caterpillar Tractor 00., Peoria, 111., a corporation California Application September 80, 1948, Serial No. 51,987

2 Claims. (Cl. 121-41) This invention relates to hydraulic jacks of the kind generally referred to as boosters and'more particularly to a double acting hydraulic jack or booster particularly adapted for use in an automotive-type transmission or the like.

It is conventional practice in heavy automotive-type vehicles to employ hydraulic boosters for actuating various control elements associated with the steering mechanism, the transmission gear shifting mechanism, the master clutch and the like. Such boosters usually comprise a piston actuated by fluid under pressure from a suitable pump and a control means for directing the flow of fluid to the piston. In the past, boosters of this type have been entirely dependent on a supply of fluid under pressure for their operation with the result that failure of the fiuid supply resulted in the operator being unable to actuate the controls.

It is an object of the present invention to provide a double acting hydraulically actuated booster capable of being readily and easily manuiactured and which will automatically be actuated mechanically in the event that the supply of fluid under pressure is not available. Other objects and advantages of this invention will be made apparent in the following specification wherein reference is made to the accompanying drawings.

In the drawings:

Fig. 1 is a longitudinal sectional view through a vehicle clutch housing illustrating a typical application of a hydraulic booster;

Fig. 2 is a longitudinal sectional view through a booster incorporating the present invention;

Fig. 3 is a development of a section taken along the line IIIIII of Fig.

Fig. 4 is a sectional view taken along the line line IV-IV of Fig. 3;

Fig. 5 is a sectional view taken along the line VV of Fig. 3;

Fig. 6 is a modified form of the neutralizing mechanism illustrated in Fig. 3; and

Fig. 7 is a sectional view taken along the line VII-VII of Fig. 6.

Figs. 1 and 2 of the accompanying drawings illustrate a double acting hydraulic booster embodying the present invention in its association with a control lever ill for effecting engagement or disengagement of a vehicle clutch or the like (not shown). The booster comprises a housing ii having a radially extending flange i2 secured by means of cap screws It to a wall of a housing i4 enclosing the clutch mechanism. The booster housing ii is provided with a cylindrical bore II, the ends of which are closed by cover plates l4 secured to the housing by means of cap screws ii. A piston i3 is disposed for reciprocation within the bore l5 and is provided with a pair of opposed extending stem portions i9 and 2|), each extending through a suitable aperture provided in the adjacent end cover It. The stem i3 is formed integrally with the piston it while the stem 20 is formed from a separate piece rigidly secured to the piston by means of a split ring 22 and cap screws 23. At its extending end, the stem 20 carries a pin 24, the ends of which are received within recesses 28 provided in the bifurcated end of the clutch control lever II in such a manner that movement of the piston it causes the control lever to rock about its supporting axis to eflect engagement or disengagement of the clutch mechanism (not shown).

The piston contains an elongated bore 21 for the sliding reception of a valve spool 23, the manipulation of which efl'ects distribution of fluid under pressure to either side of the piston for actuating the control lever I 0. The extending end of the valve spool carries a collar 29 having a threaded connection therewith which is provided with a pair of extending arms 30, received within slots 3i formed in the end of a bifurcated lever 32 nonrotatably supported on a shaft 33. The shaft 33 extends through and is supported for rotation in a housing 34 enclosing the mechanism and secured to the housing ii by means of cap screws 35. A lever 33 is non-rotatably secured to the extending end of the shaft 33 and is pivotally connected to a manually controlled link 31 which may extend to the operator's station.

The piston i3 is normally actuated by fluid under pressure from a suitable pump illustrated at 33. Fluid such as oil contained within the housing i4 is admitted to the pump through an inlet line 39 and is directed through a pressure line 4| to a fitting 42 rigidly secured to the housing 34 by any suitable means (not shown). From the fitting 42, the fluid is admitted to an axial bore 43 provided in the valve spool by means of a tube 44, one end of which is received within the bore 43 forming a sliding connection therewith. From the bore 43, the oil is admitted to connected to the piston itself. The purlof the plug it is to react the fluid pressure within. the bore 43 under certain conditions of operation that will be more fully described later in the specification.

The valve spool 28 is provided with a pair of spaced integral collars II and ii which cooperate during its sliding movement'with a pair of recesses 52 and 53 formed in the bore 21 of the piston to effect direction of the fluid therethrough. The recesses are connected by a bore 84 having a diameter less than that of the recesses but greater than that of the bore 21. The diameter of each of the collars II and II is substantially the same as that of the bore 54 and they are adapted to enter therein preventing communication between the recess 52 and 53 upon manipulation of the valve spool within the bore 21. The piston i8 is provided with a pair of passages 55 and 56, the passage 55 providing communication between the recess 52 and the bore I! on the right hand side of the piston as viewed in Fig. 2, while the passage provides communication between the recess 53 and the bore ii on the opposite side of the piston.

The valve spool is normally retained in a neutral position such as is illustrated in Fig. 2 by means of a spring I! interposed between a pair of thrust washers it and 5!. The washer 55 is adapted to abut a shoulder formed at the end of a counterbore 6i provided in the bore 21 and a shoulder formed at the end of a portion of reduced diameter 62 provided on the valve spool 2!. The washer II is adapted to abut a flange it formed on a nut 64 having a threaded connection with the end of the valve spool and one end of a sleeve 4 disposed within the counterbore 6!. The sleeve a is free to slide within the counterbore II but is normally urged into abutment with the end ll of plug 46 by the action of the spring 51. Thus, when the valve spool is moved in either direction with respect to the piston, the spring I! will be deflected urging the spool to return to the neutral position.

With the valve spool in the neutral position, fluid admitted to the bore 43 of the valve spool is directed through apertures 45 to the bore 54 in the piston where it divides and flows into recesses 52 and 53. From the recess 53, fluid is free to flow through a plurality of slots 65 extend longitudinally along the periphery of the valve spool into the housing 34. From the housing 34, the fluid is returned to the housing I by way of a passage 66 provided in the wall of the housing It adjacent to the housing 3|. From the recess 52, the fluid flows through a second set of slots 61 extending longitudinally along the periphery of the valve spool 28, through a pair of apertures it into the bore 43. From the bore H, the fluid is free to flow through a plurality of reliefs 6! formed in a collar II on the stem 41 of the piston out into the housing I 4. In order to prevent a hydraulic lock forming in the counterbore I, by the action of the washer II, it is vented to the bore 4! by a pair of apertures II.

In operation, movement of the valve spool to the right, as viewed in Fig. 2, until the collar ii abuts a shoulder 12 formed by the intersection of the recess 53 and the bore 21 directs all of the fluid entering the recess 53 through the passage 56 to the bore I! thus exerting fluid prasure on the left hand side of the piston urging it to the right. Movement of the valve spool to the left until the collar 5| abuts a shoulder 13 formed by the intersection of the recess I! with the bore 21 4 directs the fluid entering recess I! through 9 sage 55 to bore It thus exerting fluid pressure on the right hand side of the piston. urging it to the left as viewed in Fig. 2.

It is during operation toward the left, as just described, that the plug it comes into action. Upon release of the valve spool 28, the spring I! would not be able to overcome the pressin-e within the bore 43 if such pressure were acting in an axial direction upon the valve spool. as this pressure is acting on the plug 4! and through it on the piston It, the valve spool is free to be returned to its neutral position by action of the spring 51.

In the event of failure of the oil supply, the piston It can be mechanically actuated in either direction due to the abutment of the collars II and SI with the shoulders I3 and 12 respectively. At this time, there would be a direct mechanical connection between the valve spool and the piston permitting manual shifting of the control lever II. It is not intended that this will occur under normal conditions; however, it is desirable to provide a means of mechanically actuating the con trol lever during times of emergency.

Figs. 3, 4 and 5 illustrate a modification of the booster just described which is adapted to be connected in series in a common hydraulic circuit with other hydraulic mechanisms or the like. The booster comprises a housing I! having a central bore It, the ends of which are closed by cover plates 11 secured to the housing by means of cap screws II. A piston I! having end faces II and ii is disposed for reciprocation within the bore 16. Each face is in abutment with a sleeve 02 extending through and supported for reciprocation in end covers 11. At their outer ends, each of the sleeves is adapted to abut one of a pair of' spaced arms 83 carried on and secured as by cap screws 83' to a link, a part of which is illustrated at at which may extend to any suitable mechanism such as the clutch control lever ll illustrated in Fig. 1.

A valve spool 85 is disposed for reciprocation in an axial bore 0i provided in the piston II. The valve spool is provided with raised lands .1, ll and 89 which cooperate with recesses ll, 02 and 93 formed in the bore II. The ends of the valve spool are provided with recesses M and ii, the recess 9i communicating with the bore ll through spaced apertures 9i and 91 while the recess ll communicates with the bore '6 by way of spaced apertures 9t and 99. The valve spool II is interposed between a pair of plungers Ill, each of which is received within a recess ill provided in each of the sleeves l2. Each plunger is provimd with a flanged end III which is in abutment with the adjacent end of the valve spool and at its 09- posite end extends through an opening ill prm vided in each of the arms '3 and shuts the threaded end of a cap screw ill carried in an arm ll! forming a part of a manually controlled shifter yoke I. The yoke I" carries an arm ill rigidly secured thereto which may extend to within easy reach of the operator permitting manipulation of the valve spool 85 within the bore of the piston.

The diameter of the flanged end ill of the plungers I" is larger than that of the lands 1, II and 89 thus permitting the operator to feel the build up of fluid pressure acting on either face of the piston. This difference in area also serves automatically to return the valve spool to a neutral position wherein the pressure acting II on each face of the piston is equal. The tend- Howeven.

ency of the fluid pressure to neutralize the valve spool with respect to the piston is augmented by springs I08, one of which is interposed between the flange I02 and the end of the recess III in each sleeve. The face of the flange I02 opposite from the piston is adapted to engage a shoulder I 09 formed by a suitable counter-bore in each sleeve. Engagement of the flange I02 with the shoulder I09 limits axial movement of the valve spool within the bore 86 of the piston under the influence of fluid pressure acting on the ends of the recesses 94 and 95. Each of the sleeves 82 is provided with an aperture III which permits any oil which may enter the bore I| around the flange I02 to escape, thus preventing a formation of a hydraulic lock within the recess during manipulation of the valve 89001.

The piston 19 is provided with longitudinally extending slots H2, H3, H4 and H5 (Figs. 4

and 5) equally spaced about its periphery. Slots H2 and H4 are diametrically opposed to each other and are connected by a passage I I6 extending transversely through the piston. The slots H3 and H5 are diametrically opposed to each other and are connected by a pair of passages I I1 and II 8. The passage H6 intersects and communicates with the recess 92 provided in the bore of the piston while the passages H1 and H8 intersect and communicate with the recesses 9| and 93 respectively. Fluid under pressure is admitted to the housing by way of an inlet line I2| having a threaded connection with a port I22 provided therein which registers with the slot H2, and is discharged through a second port I23 which registers with the slot H5. A discharge line I24 has a threaded connection with the port I23 and may extend through an elongated opening I25 provided in the yoke I06 to a similar mechanism or the like (not shown). By provid-. ing communication between diametrically opposed slots, fluid pressure acting on the periphery of the piston is balanced preventing binding of the piston in the bore 16 during reciprocation. The piston is prevented from rotating relative to the housing by a roller I26 received within the slot H4 and carried for rotation on the extending end I21 of a cap screw I28 having a threaded connection with the housing 15. The roller permits free reciprocation of the piston in the bore but prevents rotation therein, thus insuring continuous registry of the ports I22 and I23 with the slots H2 and H5 respectively.

In operation, when the valve spool is in the neutral position such as is illustrated in Fig. 3, fluid under pressure in the slot H2 is admitted to the recess 92 by way of passage IIi where it is divided and may flow through the bore 36 into recesses 9| and 93. From the recesses 9| and 93, fluid is free to flow through passages H1 and H8 into slot H5 and is discharged through pipe I24. When it is desired to actuate the link 84 to the right as viewed in Fig. 3, the valve spool is moved to the right by manipulation of the manual control I01 until the flange I02 of plunger I00 abuts the face 80 of the piston. At the same time, the land 88 enters the bore 86 between recesses 92 and 93. Simultaneously, the land 81 closes off recess 9|, thus all of the fluid in the chamber 92 is directed through apertures 91 into recess 94 and thence outwardly through apertures 96 through a plurality of slots I26 provided in the face 80 of the piston. Thus, all of the fluid is directed against the face 80 moving the piston to the right, imparting a like motion to the link 84. During movement of the piston to the right, the fluid in the bore 16 adjacent to the face 8| will be displaced through slots I21 provided therein and directed through apertures 99 into the bore 95. From the bore 95, the fluid is directed to the recess 93 through aperture 93 and is then free to flow through passage H0 into slot H5 and is discharged through pipe I24. Upon release of the manual control lever I01, the valve spool is returned to a neutral position with respect to the piston by the springs I08.

Movement of the link 84 to the left is accomplished by movement of the valve spool to the left, at which time, the land 88 enters the bore between recesses 9| and 92 and simultaneously the land 89 blocks off the recess 93. At this time, fluid in the recess 92 is directed through apertures 98 into recess 95 and thence through apertures 99 and slots I21 into bore 16 adjacent to face 8|, thus moving the piston to the left. During movement of the piston to the left, the fluid in the bore 16 adjacent to the piston face is displaced through slots I26, apertures 96, into recess 94 and thence through apertures 91 into recess 9|. From the recess 9|, the fluid is directed through passage I I1 into the slot I I5 from which it is discharged through pipe I24. In the event of failure of the fluid supply, the piston 19 can be mechanically actuated by virtue of the flange I02 of plungers I00 abutting the adjacent piston faces.

Figs. 6 and 7 illustrate a modification of the sleeves 82 and plungers I00, illustrated in Fig. 3, in which like parts are identified by the same reference characters primed. In this modification, the spring I08 is interposed between the end of a recess IN and a washer I3I. The washer is provided with a pair of diametrically opposed ears I32 extending outwardly from its perimeter and adapted to abut a shoulder I33 provided on the sleeve 82' and extending inwardly into the recess |0| The washer is also adapted to abut a shoulder I34 formed on a plunger I00 thus positively limiting the maximum expansion of the spring. By so limiting the expansion of the spring, the neutral position of the valve spool is positively established.

Slots I35 are provided in the shoulder I33 to permit the washer |3I to be inserted into the recess I 0|. The plunger I 00' is provided with a slot I38 extending longitudinally along its circumference for the reception of a tang I31 extending inwardly from the washer I3I as well as a similar tang I38 extending inwardly from the end of the sleeve 82'. To assemble this mechanism, the washer |3I is placed on the plunger with the tang I31 in the slot I36 and then inserted into the recess IOI' by aligning the ears I32 with the slots I35. The plunger and washer are then rotated ninety degrees until the slot I36 is in alignment with the tang I30, thus looking the assembly in its operating position.

I claim:

1. In a hydraulic boster or the like which includes a cylinder and a piston reciprocal therein and carrying a hollow .piston rod, a valve spool in said rod operable to direct fluid under pressure to the cylinder selectively at opposite sides of the piston, said valve spool having an axial bore through which the fluid is introduced, and a sliding closure in said bore supported by the piston rod to prevent fluid pressure within the spool from holding the spool against free axial movement.

2. In a hydraulic booster or the like including 14 a fixed cylinder, a piston reciprocable therein, a 

